It is often necessary to transport electrical energy considerable distances from the point of its generation to the ultimate residential or commercial customer. Generally, the greater part of the distance is taken up by high voltage transmission lines. At the generating station, voltage is stepped-up to higher values by means of transformers. By the same token, transformers are used to step-down the voltage to less dangerous levels near the point of final use. The underlying purpose of this is to reduce losses that normally would occur when transmitting electricity over long distances.
Normally, the electric utility's transformer stations are outdoor facilities and the equipment there is exposed to the elements. While such facilities must be walled or fenced-in to guard against the intrusion of unauthorized people or large animals, the accessibility of these facilities, and the equipment deployed therein, to birds and small mammals, such as squirrels, can create problems.
The most serious of these problems is represented by the strong likelihood that one of these animals will electrocute itself when, while grounded, it comes into contact with an energized conductor. While this will certainly kill the animal representing a senseless loss of wildlife, more serious, from the utility's point of view, is the short circuit that occurs in the system, causing protective circuit breakers to open. The resulting power outage, and possible damage to equipment, not only causes inconvenience to the utility and its customers, but also leads to a loss in revenue and further costs for resorting service.
A critical location on these large electrical components that is frequently involved in such occurrences is the point where a bare conductor is connected to an insulator bushing. The animal, standing atop the grounded cabinet housing the equipment, is quite frequently able to reach and touch the uninsulated conductor. A convenient path to ground through the body of the animal is thereby made available and leads to the short circuit and shut-down mentioned above.
Numerous approaches toward solving this problem have been attempted. In a sense, all have the goal of extending the distance over which insulation is provided on the conductor, thereby making it more difficult for an animal to bridge the gap between the conductor and ground with its body. Among the most elementary of these attempted solutions are insulating tape or insulating pads to cover the energized conductor. These methods are generally ineffective in providing consistent protection.
Protective covers to isolate electrically energized parts represent another approach. One of the prior art protective cover designs is a one-piece plastic unit having openings at both ends for passing a cable therethrough. One end, through which the cable exits, is conical; the other, which fits over the insulator bushing, is tubular. Among its drawbacks is that nesting insects, such as wasps and bees, can enter through the bottom and establish a colony. In the event that work later must be done on the equipment, they would have to be contended with. Equally troublesome, its one-piece construction complicates retrofitting, as the electrical connection must be opened so that the guard can be slid onto the conductor. The electrical connection must then be re-established and the guard pushed down into place.
Another prior art design is for a two-piece cover. The top of this design forms a dome having an aperture in the center thereof. The bottom is tubular in shape and has a large opening. This design also has knock-outs for limited uses. The large bottom opening and the unprotected top opening permit wasps and bees to enter and nest inside. Futher, this design is also difficult to assemble and install.
Still another prior art design provides a wildlife guard comprising a one-piece tubular body, hinged in order to open in the form of two joined semi-cylinders. The other edges of the semi-cylinders include coupling means designed to engage upon closing. There are holes at both ends to accommodate the conductor and the insulator bushing. Also included around these holes are flexible fingers, whose purpose is to prevent the entry of bees and wasps. While this device generally serves its purpose quite well, it still suffers from the drawback of being difficult to install without completely shutting the equipment down.
As can be seen from the above discussion, in this field there still remains a need for an insulating cover which is more versatile, easily installed without the necessity of shutting down the equipment, and which provides greater protection both from and to animals.